DE2612846C3 - Process for producing a water-absorbent resin - Google Patents

Description

The invention relates to a method for producing a water-absorbent resin, in particular one those based on strength. -to

So far, nonwovens, papers, pulps, sponge-like urethane resins, natural sponges, etc. have been used as a water-absorbing material for sanitary napkins, diapers, disposable kitchen wipes, etc. However, such a material has little v> water absorption capacity and is therefore not sufficient for the above purposes. In recent years, cross-linked polyethylene oxide, cross-linked polyvinyl alcohol and hydrolyzed products of starch-poly-> u acrylonitrile-grafted polymer have appeared as replacements for such material. From a publication in J. of Applied Polymer Sci. 9 (1965), No. 11, pp. 3721-3736, it is known to graft alkyl acrylates onto cotton, the grafting being carried out in the presence of formaldehyde as a crosslinking agent>->. However, these products still have the drawbacks that their already relatively high water absorbency is insufficient, that they are expensive because of the difficulties in the manufacturing process, that some of them have problems when they are destroyed, that they do not biodegrade, etc.

Therefore, the object of the invention is an easily practicable process for the production of resins, the high Have water absorbency. ι> ->

Another object of the invention is a resin which has high water absorbency and good biological properties Degradable wedge united.

These and other objects which can be seen from the description are achieved by the method according to the invention solved, which consists in that one

(A) at least one strength with

(B) at least one monomer with a polymerizable Double bond that is water-soluble or becomes water-soluble through hydrolysis and

(C) polymerizing a crosslinking agent with each other and, if necessary, hydrolyzing the resulting product and adjusting the water adsorbability of the resin to at least 60 ml / g.

The subject of the invention is the method according to claim 1.

The starches used in the present invention are not particularly limited. Take natural as an example Starches such as sweet potato starch, potato starch, wheat starch, Corn starch, rice starch, tapioca starch etc. and processed or modified starches such as «starch, Dextrin, oxidized starch, dialdehyde starch, alkyl etherified Starch, allyl-etherified starch, oxyalkylated starch, aminoethyl-etherified starch, cyanoalkyl-etherified Strength etc mentioned.

Under your According to the invention usable starches are in particular natural starches such as wheat starch, Corn starch and starches derived therefrom are preferred.

Among the water-soluble monomers used according to the invention are monoethylenically unsaturated Compounds or compounds having a polymerizable double bond with at least one hydrophilic Remainder such as a carboxylic acid, carboxylic acid anhydride, carboxylic acid salt, sulfonic acid, sulfonic acid salt Hydroxyl, ether, amide, λιτιϊηο and quaternary Ammonium salt group. Practical examples of water-soluble monomers are:

(1) Monomers containing carboxylic acid groups:
monoethylenically unsaturated mono- or polycarboxylic acid [such as {methacrylic acid (acrylic acid or methacrylic acid, similar terms are used below) maleic acid and fumaric acid];

(2) Monomers with carboxylic acid anhydride groups:
monoethylenically unsaturated polycarboxylic acid anhydrides (such as maleic anhydride);

(3) Monomers with carboxylic acid salt groups:
water-soluble salts (alkali, ammonium, amine salts, etc.) of monoethylenically unsaturated mono- or polycarboxylic acids [such as sodium (meth) acrylate, trimethylamine (meth) acrylate, triethanolamine (meth) acrylate, sodium maleate, methylamine maleate];

(4) Monomers with sulfonic acid groups:
aliphatic or aromatic vinylsulfonic acids (such as vinylsulfonic acid, allylsulfonic acid, vinyltoluenesulfonic acid, styrene sulfonic acid), (meth) acrylic sulfonic acids [such as sulfopropyl (meth) acrylate, 2-hydroxy-3- (meth) acryloxypropylsulfonic acid,

(5) Monomers with sulfonic acid salt groups:
Alkali, ammonium or amine salts of the above-mentioned monomers with sulfonic acid groups.

(b) Monomers with hydroxyl groups:

mono-ethylenically unsaturated alcohols [such as (meth) allyl alcohol], mono-ethylenically unsaturated Ethers or esters of polyols (alkylene glycols,

Glycerine, polyoxyalkylene polyols), such as hydroxy (meth) acrylate, Hydroxypropyl (meth) acrylate, triethylene glycol methyl acrylate, poly (oxyethylene oxypropylene), Glycol mono (meth) allyl ethers (in which the hydroxyl groups are etherified or esterified could be).

(7) Monomers with amide groups:
(Meth) acrylamide, N-alkyl (meth) acrylamides

(such as N-methylacrylamide, N-hexylacrylamide),
N, N-dialkyl (meth) acrylamides

(such as N.N-dimethylacrylamide,

N.N'-Di-n-propylacrylamide),
N-hydroxyalkyl (meth) acrylamides

[like N-methylol (meth) acrylamide,

N-hydroxyethyl (meth) acrylamide],
N, N-dihydroxyalkyl (meth) acrylamides

[like N, N-dihydroxyethyl (meth) acrylamide],
Vinyl lactams

(like N-vinylpyrrolidone),

(8) Monomers with amino groups:
Amino group-containing esters (e.g. dialkylaminoalkyl esters, dihydroxyalkylaminoalkyl esters, morpholinoalkyl esters, etc.) of monoethylenically unsaturated mono- or dicarboxylic acids [such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, morpholinoethyl ( [such as vinyl pyridines (e.g. 2-vinyl pyridine, 4-vinyl pyridine, N-vinyl pyridine), N-vinyl imidazole, and

(9) Monomers with quaternary ammonium salt groups:

N, N, N-trialkyl-N- (meth) aLry'oyloxyalkylammonium salt

[like N, N, N-trimethyl-N- (meth) acryloyloxy-

ethylammonium chloride,

N, N, N-triethyl-N- (meth) acryloyloxyäthyl-

ammonium chloride,

2-hydroxy-3- (meth) -acryloyIoxypropyltri-

methylammonium chloride] and
Monomers mentioned in GB-PS 10 34 296.

According to the invention, monomers used instead of or in conjunction with the water-soluble monomers, which become water-soluble by hydrolysis are, for. B. monoethylenically unsaturated compounds with at least a hydrolyzable group such as an ester or nitrile group. As monomers with ester groups can e.g. B. the following are listed: lower alkyl (Ci ~ C3) esters of monoethylenically unsaturated carboxylic acids, such as methyl (meth) acrylate, ethyl (meth) acrylate, 2-Ethylhexyl (meth) acrylate and esters of monoethylenically unsaturated alcohols [vinyl esters, (meth) allyl esters etc.] such as vinyl acetate or (meth) allyl acetate. As an example of the monomers with nitrile groups Called (meth) acrylonitrile.

For the simplest possible method for the production of water-absorbent resins are under these monomers with a polymerizable double bond that are soluble in water or by hydrolysis become water-soluble, the water-soluble monomers that do not require hydrolysis after polymerization, preferred. Furthermore, from the point of view, water-absorbent resins having high water-absorbency are used to obtain, among the water-soluble monomers, the carboxylic acid-containing monomers such as (Meth) acrylic acid and maleic anhydride; the mono-

mers with a carboxylic acid salt group such as sodium (meth) acrylate, Trimethylamine (meth) acrylate, triethanolamine (meth) acrylate and monomers with a quaternary ammonium salt group such as Ν, Ν, Ν-trimethyl-N- (methjacryloyloxyäthylammoniumchlorid preferred. In order to obtain water-absorbent resins having high water-absorbency, it is preferable to use the Above-mentioned carboxylic acid group-containing monomers are used and then those after the polymerization

neutralized in obtained polymers with an alkali.

The crosslinking agents (C) used according to the invention can be any reagents which together result in reaction products crosslinked with the polysaccharide (A) and the monomer (B). As a network

ii return means can e.g. B. (1) Connection with at least two polymerizable double bonds, (2) compounds having at least one polymerizable double bond and at least one functional group which reacts with the monomer (B), (3) compounds having at least two functional groups which react with the monomers (B), and (4) compounds polyvalent metals that can generate ionic cross-links can be used.

Examples of the compounds (1) with at least

2t two polymerizable double bonds are:

(I) Di- or polyvinyl compounds (such as divinylbenzene, Divinyltoluene, divinylxylene, divinyl ether, divinyl ketone, trivinylbenzene),

(Ii) Di- or polyesters of unsaturated mono- or polycarboxylic acids with polyols [such as di- or tri- (meth) acrylic acid esters of polyols (such as, for example, ethylene glycol, trimethylolpropane, glycerine, polyoxyethylene glycols, polyoxypropylene glycols, etc.), unsaturated polyesters (the by reaction ^{!) with} any of the above polyols

an unsaturated acid such as maleic acid), di- or tri (meth) acrylic acid esters, d'e can be obtained by reacting polyepoxide with (meth) acrylic acid],

(III) ßis (meth) acrylamides such as Ν, Ν-methylene-bis-acrylamide,

(IV) Carbamyl esters, which are obtained by reacting polyisocyanates (such as tolylene diisocyanate, hexamethylene diisocyanate, 4,4'-divinyl methane diisocyanate, etc. and NCO-containing prepolymers, which by Reaction of such a diisocyanate with compounds containing active hydrogen atoms, obtained) with monomers containing hydroxyl groups, such as di- (meth) acrylic acid carbamyl ester, obtained by reacting the above-mentioned diisoxyanate with hydroxyethyl (meth) acrylate,

(V) Di- or poly- (meth) allyl ethers of polyols (such as alkylene glycols, glycerine, polyalkylene glycols, polyoxyalkylene polyols, carbohydrates, etc.) such as polyethylene glycol diallyl ether, allylated starch, allylated cellulose,
(VI) Di- or polyallyl esters of polycarboxylic acids, such as

Diallyl phthalate, diallyladipate etc. 'and
(VM) Esters of unsaturated mono- or polycarboxylic acids with mono (meth) allyl ethers of polyols, such as (methacrylic acid ester of a polyethylene glycol monoallyl ether.

hi To the connections (2) with at least one hydrolyzable double bond and at least one functional group associated with the monomer (B) can react include ethylenically unsaturated

Compounds with at least one group that is linked to a carboxyl, carboxylic acid anhydride, hydroxyl, Amino or amide group can react. Examples of these compounds are N-methylol (meth) acrylamide, Glycidy! (Meth) acrylate etc.

The compounds (3) with at least two functional groups which are associated with the monomers (B) can react, include di- or polyfunctional compounds that react with carboxyl, carboxylic acid anhydride, Hydroxyl, amino or amide groups react. Examples are glyoxal; Polycarboxylic acids such as phthalic acid or adipic acid; Polyols such as ethylene glycol; Polyamines, such as alkylenediamines (e.g. ethylenediamine), polyalkylenepolyamines, etc.

The compounds of polyvalent metals (4) that can form ionic cross-links include Oxides, hydroxides and salts of weak acids (e.g. carbonate, acetate, etc.) of alkaline earth metals (e.g. Calcium, magnesium) and zinc, such as B. calcium oxide or zinc diacetate. These compounds are more multivalent Metals can be used together with the monomer (B) containing a carboxyl or sulfonic acid group will.

Among these crosslinking agents (C), the diesters of (meth) acrylic acid with an alkylene (C ₂ ~ C ₆ ) glycol, polyoxyalkylene ~ Gi) glycol with a molecular weight below 400, bis (meth) acrylamide, alkaline earth oxide and zinc oxide are preferred.

The crosslinking agent used in the present invention improves the water absorbency against a non-crosslinked polymer considerably.

The proportions of (A), (B) and (C) can vary widely; H. in such an area that the resulting polymer has high water absorbency and water insolubility. The weight ratio from (A): (B): (C) is generally 100: 10-3000: 0.0001-20, preferably 100: 50 - 1000: 0.001-10 and especially at 100: 100-500: 0.01-5.

In addition to the constituents (A), (B) and (C) which are absolutely present, according to the invention other comonomers such as styrene, ethylene, propylene, butene, methyl (meth) acrylate, etc. can be used.

The starting compounds (A), (B) and (C) can be reacted by various processes. To the For example, the polymerization can be carried out by taking a mixture of (A), (B) and (C) Sets polymerization conditions, or the crosslinking agent (C) to the reaction product of (A) and (B) is or (C) is added to the reaction mixture of (A) and (B) during the reaction.

When the starting material (A) is not a «starch. it is advantageous to convert them to the type beforehand, for example by heating them in a solvent such as water, alcohol or a water / alcohol mixture. The temperature for conversion to the n-type can vary within a wide range, depending on the nature of the starch and the duration of the heating. It is generally between 40 and 100 ⁰ C. The polymerization can under irradiation with radioactive rays, Elcktroncnstrahlen, UV Strahlcn etc., or in the presence of a catalyst for radical polymerization such as a redox catalyst of cerium salt type. Hydrogen peroxide or a redox catalyst of the type hydrogen peroxide. Benzoyl peroxide, A / o-bis-isobiityro-nitrile. A / o-bis-isov.ilcriansäiire. Ammonium persulfate or sodium persulfate or an Rcdo ^ -catalvsator can be carried out by the persulfate. Among these polymerization methods, polymerization is preferably carried out with a cerium salt type or hydrogen peroxide type catalyst in order to increase the graft polymerization ratio between (A) and (B) and obtain a water-absorbent resin having high water-absorbency, which is an object of the present invention.

If necessary, in the case of the polymer according to the invention

K) rization a solvent such as water, methanol, Ethanol, acetone, N, N-dimethy! Vormamid, dimethyl sulfoxide or mixtures thereof can be used. the The polymerization temperature required when using a catalyst depends on the type of catalyst used Catalyst from, but is generally between 10 and 150 ° C, preferably 20 and 100 ° C.

In the case where a monomer is used alone or as part of the monomer (B) obtained by hydrolysis becomes water-soluble, the hydrolyzable groups of the monomers become after the polymerization of (A). (B) and (C) partially or fully hydrolyzed. the Hydrolysis can be carried out by any known method. In general, the However, hydrolysis in an aqueous solvent

>> or in a mixed solvent of water and alcohol Lö '-. Ingsmittel using a catalyst such as sodium hydroxide or potassium hydroxide, etc. and at a temperature between 10 and 15O ⁰ C instead. If in the resin obtained free carboxylic acid groups or

J (I sulfonic acid groups, etc. are present, these Acid groups by any conventional process for the formation of a salt (such as alkali salt, ammonium salt, Amine salt etc.) are neutralized.

The reaction product obtained according to the invention

Ji can then be dried and used to form the final product polymerized or, if necessary, washed with a mixed solvent of water and alcohol and then dried and pulverized into the final product. The reaction product can also

4 «can be diluted with water or after drying and pulverizing are dispersed in water to form a dispersion as a final product.

The water-absorbent resins obtained according to the invention can contain fillers, fiber material (such as

π pulp, cotton, etc.), pigments, UV-absorbing agents, antioxidants, chemicals for agriculture (such as fungicides, bactericides, insecticides, herbicides, fertilizers), perfumes, deodorants, etc. or mixed with it.

ν) For the water-absorbent obtained according to the invention Resins have a wide range of uses. For example, if the Resins as absorption equipment for absorbing body fluids (v / ie paper diapers, monthly

) 3 tie, gauze, paper towels etc) can be used ; Products with excellent liquid absorbency can be obtained. When mixed with soil, they can increase the water retention properties of the soil; if you for

Wed building materials for interior construction or interior decoration are used, they result in products with condensation-preventing properties, and agricultural chemicals, Fertilizers, perfumes, etc. can keep their effectiveness longer when the resins are with them

h-, are impregnated.

The water-absorbent obtained according to the invention Resins can be used and further processed according to known methods. So it can llar /

ζ. B. in powder form with pulp, earth. Plastic or the like are mixed. Rs can be in the form of a aqueous dispersion on a cellulose substrate. Cloth. Paper. Wood, stone, cement or the like can be sprayed. A substrate such as pulp, cloth. Paper. Wood. Stone, cement or the like can be put into an aqueous dispersion of the resin powder or an aqueous solution dipped in the resin and then dried. Kin substrate can be in such an aqueous dispersion or Solution and then kneaded the mixture, followed by drying. It is also possible. (A), (B) and (C) with pulp, cotton. Mixing chemicals for acriculture, perfumes or soil and then to polymerize or thereafter, if necessary, to hydrolyze and then to the final product dry.

The products with the water-absorbent resin obtained according to the present invention are various Advantages: they have excellent absorbency for Saizi solution, urine. Biut etc. next to water [the water absorbency is generally at least 60 ml / g, preferably 100 to 500 ml / g, especially 150 to 500 ml / g (active component)]; they can be stored in the atmosphere for a long time because they are extremely dry in spite of their excellent water absorbency absorb little moisture from the air; they are relatively cheap because of their ease of manufacture: there Starch is used as part of the compulsory ingredients, they exhibit excellent biodegradability on. making them easy to handle after use: and although strength is part of the compulsory components are used, are the water-absorbent compounds obtained according to the invention Resins resistant to enzymes such as amylose. In addition, they make the fact that they are biodegradable and resistant to enzymes, particularly suitable for use in Paper diapers. Sanitary napkins etc.

The invention is illustrated in the following examples made clear. The parts mentioned in the examples are standard parts.

example 1

Seven parts of cornstarch. 200 parts of water and 1200 Portions of methanol were placed in a mil stirrer. Nitrogen inlet tube and thermometer equipped reaction flask given. The resulting mixture was stirred at 55 ° C. for 1 hour under a nitrogen atmosphere then cooled to 30 C. 120 parts of acrylamide were added to the mixture. 50 parts of an ammonium (IV) nitrate solution (! / 10MoI cerium ions in 1 N nitric acid) and 0.1 part methylenebisacrylamide and then the The reaction mixture polymerized for 3 hours at 35 "C." while stirring. It became a somewhat viscous exterior Receive suspension. A powdery product was filmed from the suspension with a water / atrnol mixture (Water / methanol = 2 10 parts by weight) and hung under reduced pressure for 3 h dried at 60 ° C. After pulverizing were 176 parts of powdered products received.

Example 2

Thirty parts of wheat starch. 200 parts of water and 600 parts of ethanol were placed in a reaction vessel as in Example 1. The mixture was stirred at 60 ° C. for 1.5 hours under nitrogen and then cooled to 30 ° C. After adding 100 parts of H \ drox \ äth \ lmc! H.ti.r \ l,) t. 50 parts of a Ammoniumccr (IV) nitrate (1/10 mole of cerium ion in IN nitric acid) and 0.1 part of methylenebisacrylamide was the reaction mixture at 45 3 C ⁿ polymerized hours with stirring. A suspension of slightly yellow, fine particles was obtained. These were filtered off from the suspension, washed with a water / methanol mixture (water: methanol = 2: 10 parts by weight) and dried for 5 hours at 60 ° C. under reduced pressure. After pulverization, 78 parts were obtained of the powdered product.

Example 3

Fifty parts of corn starch, 200 parts of water and 1000 parts of methanol were placed in a reaction vessel as in Example

r> 1 given. The mixture was stirred for 1 hour under a nitrogen atmosphere at 50 ^° C. and then cooled ^{to 30 ° C.} After adding 20 parts of acrylic acid. 80 parts of sodium aerylate, 1 part of NN-methylenebisacrylamide and 0.5 part of azobisvaleric acid (as polymer

The reaction mixture was polymerized for b h at 60 ° C. with stirring. The resulting white suspension was treated as in Example 1 to give 49 parts of a powdery product.

- "'B e i s ρ i e I 4

Fifty parts of corn starch, 200 parts of water and 1000 parts of methanol were placed in a reaction vessel as in FIG Example I given The mixture was taken for 1 h

stirred in a nitrogen atmosphere at 55 ° C and then on 30 ° C cooled. After adding 20 parts of acrylic acid. 80 parts of sodium acrylate, 40 parts of an ammonium cerium (IV) nitrate solution (1/10 mole of cerium ions in I N nitric acid) and part of N.N-methylene bisacrylamide

ι. the reaction mixture was under for 3 hours at 40'C Stirring polymerizes. The resulting suspension was treated as in Example 1 to give 138 parts of a powdered product.

Example 5

Twenty parts of potato starch and 400 parts of water were placed in a reaction vessel as in Example 1. The mixture was stirred for 1 hour under a nitrogen atmosphere at 80 ° C. to convert it to α-starch.

ι. and was then cooled to 30 "C. After adding 800 Share methanol. 40 parts of acrylamide. 40 parts of ethyl acrylate. 0.2 parts of a 30% HjOr solution. 0.1 Part L-ascorbic acid and 03 parts ethylene glycol dimethacrylate the reaction mixture was at for 3 h

Polymerized at 35 ° C. with stirring. One formed white suspension treated as in Example 1 to give 87 parts of a powdered product.

Example 6

Fifty parts of cornstarch. 300 parts of water and 1000 parts of methanol were in a reaction vessel as in Example 1 given. The mixture was stirred at 50 ° C. for 1 hour under a nitrogen atmosphere and then up

"· 30 C cooled. After Zugabc 60 parts NNN-trimethyl-N-acryloyloxyäthylammoniumchlond. 0.2 parts of NN-methylene-bis-acrylamide and 0.2 parts of a 30 ^{0 /} o aqueous Wasserstoffpcroxidlösung (as a polymerization catalyst), and 0.1 part of L-ascorbic

· ■■. The reaction mixture was left at 45 ° C. for 3 h polymerized. A white suspension was formed which was then agile as in Example 1 !! was and 103 parts powdery product resulted.

IO

Example 7

1 37 parts of corn starch and 600 parts of water were placed in a reaction vessel as in Example I. The mixture was stirred under nitrogen atmosphere for 30 minutes at 55 ⁰ C and then cooled to 30 "C. After the addition of 140 parts Acry'säure, 60 parts of acrylamide, one, -η part Äthylenglykoldimethacrylsäureester. 0.2 parts of a 30% aqueous Wasserstoffperoxidlö solution and 0.1 part of L-AscorLinsäure the reaction mixture at 35 ° C for 3 hours polymerized with stirring to give an elastic white solid. the solid was pulverized after 5 hours of drying at 60 ⁰ C under reduced pressure to give 312 parts of a white . powder 100 parts of this white powder was placed in a beaker and 400 parts of 5 ^u / o solution of sodium hydroxide in a water / methanol mixture (water: methanol = 2: 8

about 2O ⁰ C allowed to stand, dried at 60 ⁰ C under reduced pressure to give 3 h after pulverizing 118 parts of a white powder.

Example 8

137 parts of rice starch and 600 parts of water were in a reaction vessel as in Example 1 is given. The mixture was stirred at 55 ° C for 3 hours and then up Chilled to 30 ° C. After adding 200 parts of acrylic acid, 1 Part calcium oxide, 0.2 part of a 30% aqueous Hydrogen peroxide solution and 0.1 part of L-ascorbic acid were added to the reaction mixture with stirring for 3 hours Polymerized at 35 ° C. An elastic white solid was formed. This solid became 200 Parts of a 30% strength aqueous solution of sodium hydroxide were added. The mixture was at overnight Left to stand at 25 ° C., then treated as in Example 9, yielding 361 parts of a white powder.

Example 9

As in Example 1, 85 parts of corn starch and 800 parts of water were placed in a reaction vessel. That Mixture was at table for 1 hour under a nitrogen atmosphere

Liquid absorbency

80 "C to convert η Λ starch and then ^{cooled to 30 °} C. After adding 120 parts of acrylic acid. I part of trioxyethylene glycol dimethacrylate, 0.2 part of a 30% hydrogen peroxide solution and 0.1 part of L-ascorbic acid, the reaction mixture was 3 h polymerized under stirring at 40 ⁰ C. Ms formed elastomeric particles. After cooling, 120 parts of 30% sodium hydroxide solution was added to the particles and then overnight at 30 ⁰ C allowed to stand. After 5 hours of drying at 60 ° C under the particles were pulverized under reduced pressure to obtain 227 parts of a white powder.

Comparative example

Examples 4, 7 and 8 were each repeated, except that no crosslinking agents were added . This gave the water-absorbent resins A, B and C for comparison.

Example 10 (Absorption test)

The water, saline and urine absorptivities of the products obtained in Examples I to 9 and Comparative Example were measured. The method for measuring the liquid absorbency consists in placing 1 g of the products obtained according to Examples 1 to 9 and the comparative example in a beaker, adding 500 ml of the respective liquid to be absorbed and preparing a dispersion, the dispersion on a sieve of 0.147 mm clear mesh size (100 mesh) and the volume of liquid that flows through the sieve is measured. 500 ml minus this volume is the amount of liquid absorbed. For comparison, the liquid absorbency of fluff pulp is also measured. The results are given in the following table. As can be seen therefrom, the liquid absorbency of the water-absorbent resins obtained in the present invention is excellent.

No. Tested sample Liquid absorbency (ml / g) 0.5% NACl 0.1NNaOH 29 urine absorbed liquid water 40 28 27 1 product obtained according to example I. 113 34 32 30th 2 product obtained according to example 2 81 42 49 31 3 Product obtained according to Example 3 110 58 31 62 4th product obtained according to example 4 219 32 59 26th 5 product obtained according to Example 7 174 63 55 60 6th product obtained according to Example 8 215 59 76 58 7th product obtained according to example 9 198 82 86 80 8th product obtained according to example 10 351 91 4th 87 9 product obtained according to example 12 482 5 T 7th A. water-absorbent resin A 35 7th 9 8th B. water-absorbent resin B 41 8th 10 9 C. water-absorbent resin C 53 11th 7th D. Fluff pulp F. 20th

Note: The values in brackets refer to the active component.

Claims (2)

Claims: IO 1. A method for producing a resin with high water absorbency, thereby marked that one (A) at least one strength with (B) at least one monomer with a polymerizable double bond that is water-soluble is or becomes water-soluble by hydrolysis and (C) at least one crosslinking agent which (1) a connection .Tiit at least two polymerizable double bonds, (2) a compound having at least one polymerizable double bond with at least a functional group that reacts with the monomer (B), (3) a compound having at least two functional groups which _{react with the mono- 1 ()} mer (B) and (4) a compound of a polyvalent metal in the form of an oxide, hydroxide or salt of weak acids of alkaline earth metals and zinc, can be, _r _ polymerized and, if the monomer in (B) only becomes water-soluble by hydrolysis, the one obtained Product hydrolyzed, and the water absorbency of the resin to at least 60 ml / g adjusts. jo 2. The method according to claim 1, characterized in that a strength beforehand in one Solvent at elevated temperature in the -type over-felt .e strength is used.